Amy, you make very valid points about setting expectations, "playing by the rules", and CAS vs more embellished styles. However, from my friend's experience (since I don't have anything personally to go by), her disappointment was more along the lines of contrapat's - irregular layers, mis-stamped images, etc. I think that the swap hostess that she indicated was smart - exchange like for like.
Having said that, though, I'll also say this: maybe the makers of the "poor" cards are new to stamping, excited about their first swap, and just don't have the skills (yet) to do better. I personally know someone who has been stamping for a long time and LOVES it, but her abilities will NEVER match her enthusiasm! Bless her - she churns out card after card of mismatched papers, wonky images, weird embellishments, etc., and I would never dream of telling her anything negative about any of it - she's having too much fun! (She doesn't participate in swaps, though